Is it possible to see sound? Yes, but it takes some crafty photographic wizardry

The concept of ‘seeing sound’ might seem preposterous, but when you consider that sound is just compressed air travelling in waves, the idea becomes a bit more logical. The real trick is capturing air flow in a way that makes it perceptible to the human eye. Through some clever tricks, scientists are able to do just that using a technique called Schlieren flow visualisation, which is used to study everything from heat and sound to aerodynamics and the spread of disease.